Sheet stabilizer for dryer

ABSTRACT

A dryer for evaporating mositure from a traveling paper web having dryer drums arranged in upper and lower tiers with the web traveling in a serpentine path up and down over the drums and edge rolls positioned at each edge of the web against the uprunning span thereof driven at a speed approximately 75 per cent of the speed of web travel and slightly deflecting the web, preventing flutter of the edges at the higher web speeds.

United States Patent Justus et al. Apr. 8, 1975 [54] SHEET STABILIZERFOR DRYER 3.4l 1.684 I l/l968 Tison et al. 226/l95 3.5 )7 70 4 2 [75]Inventors: Edgar .l. Justus; Elmer E. Crist, o9 5H9 Hemmer 3 ll 0 bothof Below WIS. Primary Examiner-Kenneth W. Sprague gn z Beloil rpora n. mAssismnt Examiner-James C. Yeung Almrnev A em or Firm-Hill Gross Sim sonVan 22 Fld: M .16.!973 P 1 ar Santen. Steadman. Chiara & Simpson [2|]Appl. No.: 341,963

[57] ABSTRACT 7 [52] U.S. Cl. 34/118, 34/l20, 2-6/195 A dryer forevaporating mositure from a traveling [5 [1 Int. Cl. F26b 11/02 [58]Field of Search 34/1 104 paper web havmg dryer drums arranged in upperand "f lower tiers with the web traveling in a serpentine path 226/195242/752 26/63 68 up and down over the drums and edge rolls positioned[56} Reterences Cited at each edge of the web agalns t the uprunningspan thereof dr1ven at a speed approxlmately 75 per cent of UNITEDSTATES PATENTS the speed of web travel and slightly deflecting the l.0l7349 2/19l2 Tracy 34/118 web, preventing flutter of the edges at thehigher web 1.170.309 2/1916 Meyers 34/[18 speeds. 2,067755 l/l937 Dyer,Jr 34/48 2.348.!62 5/l944 Warner 26/65 9 Claims, 2 Drawing Figures SHEETSTABILIZER FOR DRYER BACKGROUND OF THE INVENTION The present inventionrelates to improvements in dryers and more particularly to dryers of thetype used in a paper making machine having a series of rotating dryerdrums over which the web is wrapped for heating the web and evaporatingmoisture therefrom.

In such dryer drums. with the increase of speed of paper makingmachines, one of the difficulties encountered has been flutter of theweb. The flutter at times tends to be progressive and will tend to tearthe sheet or at least cause uneven contact or stretching of the sheet sothat nonuniform contact between the web and drum occurs resulting innonuniform drying across the sheet. If the sheet arrives at the calenderbeing dried nonuniformly so that excess moisture remains at certainareas across the width of the sheet, calendering will be nonuniform, andthe final web wound on the take-up roll will be nonuniform makingunusable, or at least a very low quality of paper.

The fluttering which occurs at the web edge can occur at differentlocations along the dryer, but will occur at any place in the web spanas it travels from one drum to the other. Conventionally, the drums arearranged in tiers with the web traveling in an S shaped serpentine pathbetween the upper and lower tiers of the dryer. The fluttering can beprogressive across the sheet generally starting at the edge and isparticularly disadvantageous in causing stretching of the sheetparticularly if it occurs at a number of locations and a number of spansbetween dryer drums. As the web enters the dryer section, the moisturecontent decreases so that the actual weight of the web changes andfluttering can occur at various positions. Efforts to reduce thisflutter have met with varying degrees of success, but have not beenwholly capable of providing a simple effective means of eliminating theflutter particularly at high speeds.

It is accordingly an object of the present invention to provide animproved mechanism for use in a paper machine dryer section whichfunctions to eliminate web flutter between dryer drums.

A still further object of the invention is to provide an improvedmechanism for eliminating flutter in a paper machine dryer sectionbetween dryer drums and accomplishing the elimination of the flutter bya simple construction which does not require substantial space and canbe readily installed in existing dryers.

While features of the invention are capable of being used to advantagein various types of machines, they are particularly useful in theenvironment of dryers for a paper making machine and will be describedin connection with this use.

Other objects and advantages will become more apparent, as willequivalent structures which are intended to be covered herein, in theteaching of the principles of the invention in connection with thedisclosure of the preferred embodiment in the specification, claims anddrawings, in which:

DESCRIPTION OF THE DRAWINGS FIG. I is a front elevational view of apaper dryer constructed and operating in accordance with the principlesof the present invention; and

FIG. 2 is a fragmentary vertical sectional view taken substantiallyalong line IIII of FIG. 1.

DESCRIPTION As shown in FIG. I, a dryer section ofa paper making machineis supported on front and back frames with the front frame shown ashaving vertical posts 10 and II with a laterally extending beam 12therebetween The framework at the back of the machine will be somewhatsimilarly constructed and need not be shown in detail. Extending betweenthe front and back frames of the machine will be a plurality ofsequentially arranged dryer drums.

The drawings show first, second and third drums I3, 14 and 15. The drumswill be usually arranged in tiers with the drum 14 being in the uppertier and the drums l3 and 15 being in the lower tier. The upper tier ofdrums will be at the same horizontal elevation, and the lower tier ofdrums will be at the same horizontal elevation with the number of drumsprovided being sufficient to heat the web and evaporate the moisturetherefrom which is left in the web after passing through the presssection of the machine. Such machines will conventionally have or moredrums. The drums will be heated usually by steam to be at a controlledtemperature which is kept uniform throughout the length of the drum. Thelength of the drum will vary in accordance with the designed width ofthe paper making machine and conventionally will be approximately 24feet to 36 feet long.

The web W is wrapped in serpentine fashion over the drums so as totravel in a generally S shaped path. As illustrated, the web is firstwrapped over the lower drum 13 and then passes up in an upwardlyextending run W-U and is wrapped over the upper drum l4 and then extendsin a downward run W-D.

Positioned at the edges of the web W in the upwardly extending run W-Uare guide means in the form of edge rolls positioned at each edge of theweb. Because the rolls are of similar construction, only the roll 16 atthe front edge of the machine need be shown and described in detail. Theedge rolls are of limited length and do not extend completely across themachine, but extend only a short distance inwardly to contact the edgeofthe web and to deflect it a short distance D from its normal path oftravel. The edge rolls can be positioned on either side of the web, butpreferably on the same side as the lower roll which the web has justleft. It has been discovered that by merely positioning a short roll atthe edge of the web, the problems created by web flutter are avoided inthat the fluttering which seems to originate at the edge of the web doesnot begin. Also, it is at the edge of the web that the flutteringusually results in paper web stretch to cause nonuniform drying, andthis is avoided by the edge rolls. By not extending the edge rollscompletely across the web, fluttering is avoided and yet unnecessarycontact with the full width of the web has been eliminated. If a fullwidth roll were used, unnecessary air flow currents would be induced anddifficulties would be encountered in maintaining a roll of such a longwidth straight and downward bowing in such a roll would tend to have anonequal effect on the web across its width, tending to cause wrinkling.

The roll is driven in rotation in a direction the same as the webtravel, and it has been found that by driving the roll at a speed slowerthan the web travel, the tendency of the edge roll to eliminate flutteris enhanced.

A rotational speed of preferably 75 per cent of the speed of web travelis used and variations from 50 to I per cent of the speed of web travelalso may be employed. A sliding guide may also be employed. butsubstantial improvement is achieved by using a rotating roll.

The edge rolls are supported on brackets such as shown by the bracket 17mounted by a plate 18 to the beam l2. The plate is so constructed so asto permit lateral adjustment of the position of the edge roll and thismay be accomplished by elongate slots in the plate, so that it may beadjusted by loosening tightening nuts. not shown, and shifting the plateto obtain a desired web deflection D. Preferably, the deflection D foreach edge of the web is chosen to be the same.

Secured to the bracket [7 is an angle bracket 19 which supports the rollin cantilever fashion with the lower end of the bracket 19 shown at inFIG. 2. The roll I6 may be driven by separate motors, or may be drivenby sheaves carrying belts which pass over similar edge rolls. The rollin FIG. 2 is shown equipped to be driven by a sheave 23 or by a motor24. If the roll is to be usually driven by a sheave, the motor 24 may bere placed by a supporting bearing. Conversely, if a motor drive isusually to be used, the sheave 23 may be omitted.

The roll I6 comprises a tubular roll shell 16a with radial bearingplates 16d and lfie rotatably mounted on a trunnion 21. The trunnion 21is driven in rotation by the motor 24 or by the sheave 23 which islocked to the trunnion 2|. The roll is held on the trunnion shaft by anut 22 threaded on the end holding the plate l3e in place.

At the end of the roll, it is rounded in a curved shaped cone end shell16b which is held by a screw 166 to the roll shell 16a. The roll shell16a and the end shell 16b are polished for smooth nonabrasive contactwith the web. A coating of teflon may be contained on the outer surfaceof the roll and end cone.

The length of the end roll is short relative to the width of the paperweb, and a roll length of 6 inches to 4 feet may be employed. Similarly,the diameter of the roll is small relative to the dryer drums, and adiameter of 3 inches to 2 feet is satisfactory.

In addition to being positionably adjustable in a lateral direction tovary the deflection D, the roll may be vertically adjustable by thebracket 19 being vertically adjustable in its support I7. Where a motordrive is used, a variable speed motor is employed to control therotational speed of the roll to approximately 75 per cent of the webspeed. Where a sheave drive is used, the main driving motor driving thebelt will also be variably controlled in speed.

While the edge rolls may be employed in all of the open draws, it hasbeen found that by using them only in the uprunning draws, edge flutteris avoided. The rolls are simple in construction and easily manufacturedand may be used on existing paper equipment as speeds of operation areincreased.

I claim as my invention:

1. In a dryer for evaporating moisture from a traveling fibrous web, thecombination comprising:

a plurality of heated dryer drums positioned in the upper and lowertiers for having a traveling web sequentially passed between the upperand lower tiers to wrap the drums for heating the web and evaporatingmoisture therefrom;

edge rolls each having an axis parallel to the drums and parallel to theweb and at right angles to the direction of web travel, said rollspositioned between the upper and lower tiers at each edge of the webextending only a short distance inwardly from the web edge defiectinglysupporting the web edge to reduce the tendency of the sheet to flutterat high er web travel speeds;

bearing means supporting said rolls;

and fixed supports for said bearing means fixedly locating said bearingmeans and fixing the position of said axes of said edge rolls.

2. In a dryer for evaporating moisture from a traveling fibrous web, thecombination constructed in accor dance with claim I:

wherein the edge rolls are driven at a surface speed lower than thespeed of travel of the web.

3. In a dryer for evaporating moisture from a traveling fibrous web. thecombination constructed in accordance with claim I:

wherein said drums are positioned with a second drum at a higherelevation than the first drum and the edge rolls are located in the spanbetween the first and second drum and wherein a third drum is located ata lower elevation than the second drum and the web span between thesecond and third drum is free from contact with any edge rolls.

4. In a dryer for evaporating moisture from a traveling fibrous web, thecombination constructed in accordance with claim 1:

wherein said edge rolls have a generally rounded nose end inwardly fromthe edge of the web.

5. In a dryer for evaporating moisture from a traveling fibrous web, thecombination constructed in accordance with claim 1: wherein the edgerolls have a length of no greater than 4 feet.

6. In a dryer for evaporating moisture from a traveling fibrous web, thecombination constructed in accordance with claim 1:

wherein the edge rolls have a diameter in the range of 3 inches to 2feet.

7. In a dryer for evaporating moisture from a traveling fibrous web, thecombination constructed in accordance with claim I:

wherein the guide means are provided with means for adjusting theirposition relative to the plane of the sheet so that the distance thesheet is deflected from its normal path of travel between drums can becontrolled. 8. In a dryer for evaporating moisture from a travelingfibrous web, the combination comprising:

a plurality of parallel heated drums positioned so that a websequentially wraps the drums to be heated and to evaporate moisturetherefrom; and guide means at each edge of the web in the web spanbetween drums engaging the web at the edge and extending inwardly only ashort distance from the web edge preventing web flutter at higher webspeeds, said guide means being in the form of a roll at each edge of theweb and the roll being driven at a speed ranging from 50 per cent to percent of the web speed. 9. In a dryer for evaporating moisture from atraveling fibrous web, the combination comprising:

speeds.

said guide means being in the form of rolls at each edge of the web andthe rolls being driven at a speed substantially per cent of the speed ofweb travel.

1. In a dryer for evaporating moisture from a traveling fibrous web, thecombination comprising: a plurality of heated dryer drums positioned inthe upper and lower tiers for having a traveling web sequentially passedbetween the upper and lower tiers to wrap the drums for heating the weband evaporating moisture therefrom; edge rolls each having an axisparallel to the drums and parallel to the web and at right angles to thedirection of web travel, said rolls positioned between the upper andlower tiers at each edge of the web extending only a short distanceinwardly from the web edge deflectingly supporting the web edge toreduce the tendency of the sheet to flutter at higher web travel speeds;bearing means supporting said rolls; and fixed supports for said bearingmeans fixedly locating said bearing means and fixing the position ofsaid axes of said edge rolls.
 2. In a dryer for evaporating moisturefrom a traveling fibrous web, the combination constructed in accordancewith claim 1: wherein the edge rolls are driven at a surface speed lowerthan the speed of travel of the web.
 3. In a dryer for evaporatingmoisture from a traveling fibrous web, the combination constructed inaccordance with claim 1: wherein said drums are positioned with a seconddrum at a higher elevation than the first drum and the edge rolls arelocated in the span between the first and second drum and wherein athird drum is located at a lower elevation than the second drum and theweb span between the second and third drum is free from contact with anyedge rolls.
 4. In a dryer for evaporating moisture from a travelingfibrous web, the combination constructed in accordance with claim 1:wherein said edge rolls have a generally rounded nose end inwardly fromthe edge of the web.
 5. In a dryer for evaporating moisture from atraveling fibrous web, the combination constructed in accordance withclaim 1: wherein the edge rolls have a length of no greater than 4 feet.6. In a dryer for evaporating moisture from a traveling fibrous web, thecombination constructed in accordance with claim 1: wherein the edgerolls have a diameter in the range of 3 inches to 2 feet.
 7. In a dryerfor evaporating moisture from a traveling fibrous web, the combinationconstructed in accordance with claim 1: wherein the guide means areprovided with means for adjusting their position relative to the planeof the sheet so that the distance the sheet is deflected from its normalpath of travel between drums can be controlled.
 8. In a dryer forevaporating moisture from a traveling fibrous web, the combinationcomprising: a plurality of parallel heated drums positioned so that aweb sequentially wraps the drums to be heated and to evaporate moisturetherefrom; and guide means at each edge of the web in the web spanbetween drums engaging the web at the edge and extending inwardly only ashort distance from the web edge preventing web flutter at higher webspeeds, said guide means being in the form of a roll at each edge of theweb and the roll being driven at a speed ranging from 50 per cent to 100per cent of the web speed.
 9. In a dryer for evaporating moisture from atraveling fibrous web, the combination comprising: a plurality ofparallel heated drums positioned so that a web sequentially wraps thedrums to be heated and to evaporate moisture therefrom; and guide meansat each edge of the web in the web span between drums engaging the webat the edge and extending inwardly only a short distance from the webedge preventing web flutter at higher web speeds, said guide means beingin the form of rolls at each edge of the web and the rolls being drivenat a speed substantially 75 per cent of the speed of web travel.